$ { {-5} \times \left[\begin{array}{rr}{2} & {4} \\ {-1} & {0}\end{array}\right] = {?} } $
Answer: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rr}{-5}\times{2} & {-5}\times{4} \\ {-5}\times{-1} & {-5}\times{0}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-10} & {-20} \\ {5} & {0}\end{array}\right]}$